The broad objective of this program is to perform preclinical experimentation on the mouse genetic models of VEDS to test the efficacy of different therapeutic modalities to attenuate the vascular fragility and, thus, to prevent or to reduce the risk of vascular complications. With repect to specific steps outlined in Objectives, this year we concentrated on steps I and III.[unreadable] [unreadable] Characterization of existing genetic model of VEDS[unreadable] The haploinsufficiency for one COL3A1 allele is one of the genotypes resulting in VEDS. Homozygous Col3a1 mice, the only currently available and described model of VEDS, cannot be used for experiments due to extremely high prenatal mortality. We hypothesized, that heterozygous Col3a1 mice, originally described as phenotypically normal, can serve as an experimental model of haploinsufficiency. We compared aortas and colons of 9, 14 and 21 months old (+/-) and (+/+) Col3a1 mice in vivo (high frequency sonography and pressure-volume analyses) and ex vivo (histology and biomechanical properties). In all ages the aorta in +/- mice had a lower compliance, larger lumen diameter, and lower ex vivo rupture pressure, than in wild type mice. Histological evaluation of aortas of +/- mice demonstrated abnormalities among 100% of male and 50% of female mice, revealing elastin fragmentation, spindle cell proliferation, inflammation, and reactive fibrosis. The colon of +/- animals had higher compliance and lower maximal (pre-rupture) pressure (higher fragility) in 9-21 months old animals. This was associated with a lower collagen III content detected by quantitative RT-PCR and, on protein level, with peptides separated by HPLC and detected with LC-MS. Thus, the +/- Col3A1 mouse could serve as an experimental model for the VEDS.[unreadable] Development of molecular genetic tools to suppress specific mutations in tissue culture experiments[unreadable] The experiments conducted during this year led to a patent application, which is currently being filed, and thus cannot be disclosed at this time.